We shall continue our studies of normal development and congenital defects in steroid biosynthesis. The approach will involve measurement of steroid metabolites in serum and urine by competitive protein binding, radioimmunoassay and gas chromatography. We will pay particular attention to the activity of 3 Beta hydroxysteroid dehydrogenase in adolescents with known deficiency of the enzyme, normal children from birth to adolescence, infants with hypospadias, adolescents with gynecomastia, girls with gonadal dysgenesis, and males with Klinefelter syndrome. These studies will be accompanied by further studies of maturational changes in rats treated with cyanoketone, an inhibitor of 3 Beta hydroxysteroid dehydrogenase.